Beginning writers and filmmakers are always told, “Write what you know.” While that is certainly sound advice, it should come with a warning label that reads, “May lead to hurt feelings among friends and family, screaming, yelling, possible bloody nose.” Mariana Chenillo, whose superb first feature film “Nora’s Will” opens on Friday, managed to avoid all of those pitfalls, but drawing on her family history for the film’s story was not without its nervous moments.

Early in the excellent new documentary “Robert Lifton: Nazi Doctors,” co-director Wolfgang Richter expresses his concern to Dr. Lifton about the sheer immensity of the Holocaust as a topic for study. Lifton, who is the very soul of calm and equanimity throughout the film, replies quietly: “One can only do so much ... One has to fail to comprehend the entire event. It’s elusive, but one can capture or illuminate some portion of it.”